[gpfsug-discuss] Renaming Linux device used by a NSD

[Valdis Kl=?utf-8?Q?=c4=93?=tnieks]

On Tue, 18 Jun 2019 23:23:37 -0000, "Rob Logie" said:

> We are doing a underlying hardware change that will result in the Linux
> device file names changing for attached storage.

> Hence I need to reconfigure the NSDs to use the new Linux device names.

The only time GPFS cares about the Linux device names is when you go to
actually create an NSD.  After that, it just romps through /dev, finds anything
that looks like a disk, and if it has an NSD on it at the appropriate offset,
claims it as a GPFS device.

(Protip:  Since in a cluster the same disk may not have enumerated to the
same name on all NSD servers that have visibility to it, you're almost always
better off initially doing an mmcreatnsd specifying only one server, and then using
mmchnsd to add the other servers to the server list for it)

Heck, even without hardware changes, there's no guarantee that the disks
enumerate in the same order across reboots (especially if you have a petabyte
of LUNs and 8 or 16 paths to each LUN, though it's possible to tell the multipath
daemon to have stable names for the multipath devices)
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